1. Field of the Invention
This invention relates to systems, apparatus, and methods for managing data and more particularly relates to systems, apparatus, and methods for copying data.
2. Description of the Related Art
Efficient data copy/move solutions are an important aspect of managing and storing data. Data copying may include operations wherein data is moved from one location to another such as defragmenting data or backing up data. Solutions for copying data include conventional input/output (I/O) operations where a host system reads and writes data to and from a data storage device. Such an approach is effective to copy data but creates undesirable data copy overhead due to the necessary input/output operations.
Another data copy solution includes fast replication, such as IBM's FlashCopy®, where a single request is sent from a host system to a data storage subsystem and the data storage subsystem carries out the entire copy operation. Fast replication is often viewed as faster and more efficient than the input/output approach because fast replication eliminates the need for multiple input/output operations. Though fast replication may reduce the data copy overhead created by input/output operations, certain problems exist.
For example, if a host system sends a fast replication request corresponding to data already in a fast replication relationship, the fast replication request can not be performed. Consequently, the host system copies the data with conventional I/O operations because waiting for the data to become available for fast replication could take longer than copying the data with conventional I/O operations. In other words, because the host system has no way of estimating when the data will be available for fast replication, the data is copied via conventional I/O operations.
In summary, due to the problems previously described, fast replication operations remain underutilized.